Bottom-hole formation tester



Nov. 19, 1957 J. E. WALSTROM 2,813,535 I BOTTOM-HOLE FORMATION TESTERFiled March 1, 1954 2 Sheets-Sheet 1 INVENTOR JOHN E. WALSTROM w'7IATT0RNEY? (iii Nov. 19, 1957 J. E. WALSTROM 2,813,585

v BOTTOM-HOLE FORMATION TESTER Filed March 1. 1954 2 Sheets-Sheet 2 g Iis "11. 95

dllllltf- '-I 1 H INVENTOR 7 JOHN E. WALSTROM United States PatentBUTTOM-HOLE FORMATION TESTER John E. Walstrom, Diablo, Calif., assignorto California Research Corporation, San Francisco, C'alif., acorporation of Delaware Application March 1, 1954, SerialNo. 413,006

Claims. (Cl. 166-63) The present invention relates to apparatus forwithdrawing fluid samples from earth formations traversed by a borehole, more particularly to apparatus for sampling fluid content of aformation through the bottom of a bore hole and has for an object theprovision of an improved apparatus for openahole sampling in situ of thefluids contained in earth formations lying at the bottom of the borehole by reducing the hydrostatic head on a portion of said bottom whilecontrolling the vertical thrust on the body member of the samplingdevice to maintain a tight fluid seal against the bottom of anopen-full-sized bore hole both before and during withdrawal of the fluidsample, said vertical thrust being controlled by adjustment of theweight of the drill pipe supported on said body.

During the drilling of wells for oil, gas and the like, it is oftendesirable to test the fluid content of formations lying directly at thebottom of the bore hole. Such testing is often done upon obtaining anoil or gas show in the drilling fluid or cuttings that are continuouslyreceived at the surface of the well bore as a result of the circulationof the fluid stream. Heretofore, such bottomhole drill stem testing offluid content has only been accomplished by pulling the pipe and runninga drill stern testing tool utilizing one or more full hole sidewallpackers set near the bottom of the hole. In deep holes it is often notfeasible to run full hole packers to the bottom of the hole due to thesmall clearance that exists between these packers and the sides of thehole and due to other operating difliculties. In such an instance itbecomes necessary to pull the drill pipe out of the hole, put on asmaller size bit, drill ahead in small size hole, remove the drill pipeand run a drill stem tester equipped with one or more reduced-sizesidewall packers to fit the reduced hole; or a cone packer to seat onthe shoulder at the top of the reduced size hole. However, this lattertype of formation fluid testing operation is extremely costly due to thenecessity of stopping the normal drilling operation to drill a reduceddiameter hole, and subsequently requiring opening of the hole to itsfull-hole size again. Additionally, boring ahead into the formation toestablish the reduced-size hole may result in passage entirely through apotentially productive oil zone: into a water zone, shale, or otheruninteresting formation.

A principal advantage of the present invention, therefore, is that whenfull-hole packers cannot be run into the hole due to the great depth of.the hole, irregularities prevailing in the hole, or other operatingconditions, there is provided means for making a bottom hole test,without the necessity of drilling reduced hole, and the severalattendant disadvantages of such'an operation.

In accordance with the present invention, there is provided an apparatusfor bottom-hole formation testing to determine the fluid content ofearth formations lying directly ahead in a bore hole which may be usedat any time during the drilling of a well without departure fromconventional full-sized hole drilling procedures, and without requiringuse of conventional sidewall packers and their restricted clearances.Further, the formation fluid content is sampled in adequate volume toobtain a true representation of the fluid in accordance with theinvention by supporting the testing apparatus at the lower end of astring of conventional drill pipe. In carrying out the invention, a bodymember is provided with means for sealing the lower-end face portion ofthe body into engagement with the bottom of the bore hole while thevertical thrust on the body member against the bottom of the bore holeand the formation is controllably adjusted by regulating the weight ofthat portion of the drill pipe which is supported on the end face packermeans. In a preferred form of the invention, bullet or shaped-chargemeans are provided for piercing the lower face portion of the bodymember in contact with the bottom of the hole to open port means in saidsealing means and establish an elongated hole into the formation throughwhich formation fluid may readily enter the testing tool and rise withinthe drill pipe. Further, in accordance with the invention, valve meansare provided between the bottom of the drill pipe and the body member toprovide a shut-off after fluid has accumulated in the drill pipe toprevent said fluids from being pushed upward and out of the drill stemas a result of the sudden entry of drilling fluid from the bore holethrough the open port, upon unseating the testing tool from the bottom.Pressureequalizing valve means, operable when said shut-off valve meansare closed, are provided to equalize the pressure across the entranceport means and the bottom-hole packer means and permit ready removal ofthe tester apparatus.

Further objects and advantages of the present invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings which form an integral part of thepresent specification.

In the drawings,

Fig. 1 is a diagrammatic representation of a preferred form of thepresent invention illustrating the manner in which the testing tool issupported in the well bore and controllably brought into sealedengagement with the bottom of the bore hole and the formation whosefluid content is to be tested.

Fig. 2 is an enlarged cross-sectional view of the lower end of thetesting tool illustrated in Fig. 1.

Fig. 3 is a view of a portion of the testing tool showing the flow portsand firing pin in the direction of arrows 33 in Fig. 2.

Fig. 4 is an enlarged view of the lower end of the tool shown in Fig. 1,illustrating an alternative formation cutter and sealing arrangement forthe lower end of the embodiment shown in Fig. 2.

Fig. 5 illustrates another modification of the lower end of the testingtool of Fig. 1.

Fig. 6. illustrates a. further modification of the lower end of theformation. sampling tool.

Fig. 7 is an enlarged view of the pressure-equalizing valve means,illustrating its operation after withdrawal of a sample from theformation under test.

With reference to the drawings, and in particular Fig. 1, there isillustrated a preferred form of apparatus for carrying out the presentinvention, in which a fluid sampling tool 10 for withdrawing a sample ofthe fluid content of a formation 11 lying directly below the bottom ofbore hole 12 is adapted to be supported in the bore hole on a stand ofdry drill pipe, indicated generally as 1 3. Drill pipe 13, whose end isclosed by tool10, in turn, is supported. by drilling derrick 14including traveling block 15. and crown block 16 through cable 17. Aswill be understood by those skilledin the art, drill pipe 13- is raisedand lowered in the bore hole by cable 17 operating through travelingblock and crown block 16 by reeling and unreeling of cable 17 on drum18. The weight of the drill pipe 13 is arranged to be measured-by deadweight indicator 19, which is interposed between the anchor means 20 andthe dead wire line 21, the latter forming an extension of the end ofcable 17 passing downwardly from crown block 16.

The drill pipe and main body portion 26 of testing tool 10, inaccordance with the concept of the present invention, are ofsubstantially smaller diameter than bore hole 12, in order to permit thedrill string and tool to be run in and out of the bore hole withoutinterference between the bore hole walls and the tool.

Further in accordance with the present invention, during withdrawal offluid from formation 11, directly ahead of bore hole 12, and to permitsuch fluid to enter the bore hole, as well as during withdrawal offluid, the weight indicating means 19 and the pipe supporting means,including derrick 14 and cable 17, provides a means for controlling thetotal thrust of the end face, or formationengaging portion, of the body26 of fluid sampling tool 10 against the bottom of the bore hole. Thiscontrol permits a pressure differential to be established between theinlet port means formed in end face 25 and the exterior of tool 10, aswill be more fully described below.

As more fully illustrated in Figs. 2, 4, 5, and 6, the end face portion25 engaging the bottom of bore hole 12 comprises a packer means 28adapted to be deformed by the vertical thrust on body member 26 to sealthe lower end of body member 26 against the bottom. As indicated, packermeans 28 has an undeformed diameter that is substantially the same asbody member 26. The thickness or length of packer 28 is substantiallyless than its diameter so that engagement with the side walls of thefull-sized bore hole is prevented when the packer is deformed on bottom.Packer means 28 also permits the lower portion 29 of body 26 to be heldstationary while the upper portion 30 is rotated to open valve meansbetween body member 26 and pipe 13. Rotation of pipe 13 likewise servesto explode a shaped-charge 37 to rupture or pierce the bottom of thewell bore and formation 11. In the preferred embodiment of theinvention, shown in Fig. 2, a threaded plug 38 forms the inlet portmeans into the conduit formed by fluid-receiving lower chamber 50 andupper chamber 53, in lower body member 26. Threaded plug 38 alsopositions shaped-charge 37, behind a holdback plate 39, to increase thepiercing depth of charge 37 into formation 11, when detonated by theimpact of firing pin 36 on blasting cap 40 which, in turn, ignitesexplosive cord 41 thereby to detonate shaped-charge 37. As particularlyillustrated in Fig. 2, plug 38 is provided with an annular cutter 45which extends through packer means 28 so that the cutter may be broughtinto firm contact with the bottom of the well bore. Cutter 45 likewiseis arranged to pierce the mudcake 47, which normally surrounds theperiphery of bore hole 12 and which cooperates with packer 28 to sealagainst the hydrostatic head of the drilling mud. Rotation of body 26and drill pipe 13, in a normal, clockwise direction, as viewed from thetop of the bore hole, causes cutter 45 to drill slightly into formation11 and permits packer 28 to seat more firmly on bottom to bringshaped-charge 37 into more intimate contact with formation 11.

After packer means 28 is securely seated on bottom, upper portion 30 oftool 10 is then rotated in a counterclockwise direction in order toscrew threaded portion 49 of upper section 30 into the mating portion oflower section 26, thereby to open valve means 35 and permitcommunication between chamber portion 50 of lower portion 26 and theinterior of the drill pipe 13. In the present embodiment, the screwthreads on end section 49 of upper portion 30 are preferablyleft-handed, so that counterclockwise rotation of the drill string 13,with lower portion 26 held stationary by the bottom of the bore hole andthe load placed thereon, will cause valve 35 to open.

As indicated, the valve means 35 for opening chamber 50 to the interiorof pipe 13 comprises an extension section 51 on upper portion 30 of tool10, which includes an L-shaped conduit 52, which is brought intocommunication with an upper chamber 53, by the continued rotation ofupper portion 30, against the compression of spring 55. Chamber 53 islikewise opened to lower chamber 50 by the longitudinal movement ofsection 51 which causes the downward movement of valve stem 61 and valve56 away from its seat 57 in section 26.

As noted above, downward movement of upper portion 30 likewise serves toexplode shaped-charge 37 by releasing firing pin 36. Release of firingpin 36 is accomplished by lower end 60 of the valve stem 61, which isindependent of section 51, but urged downwardly by that section untilend 60 contacts the upper end of firing pin 36. Firing pin 36 isnormally held in a cooked position by compression spring 62, heldbetween a cap member 63 and a transverse wall member 64. The firing pinis retained in this position by a shear pin 65, which is arranged to besevered by a further longitudinal thrust which may be applied by endface 60 of valve stem 61.

It will thus be seen from the foregoing description that rotation of theupper section 30 not only serves to operate the multiple valvearrangement, identified as 35, but also at the end of its travel, servesto ignite the shaped-charge 37 to open a perforation into formation 1.1lying directly ahead in the bore hole. In this way, the hydrostaticpressure on that formation may be reduced through the perforation and atthe same time a flow path may be established into lower chamber 50 byrupture of disk 39. The four wear rings 70 in lower plate 71 and similarwear rings in plate 64 permit fluid to rise through chamber 53 and intothe interior of drill pipe 13 under the reduced pressure therein whichwill be substantially atmospheric. Upon completion of the bottom-holeformation test, valve means 35 may be closed by clockwise rotation ofthe upper portion 30 relative to lower portion 26, while a predeterminedweight is maintained on the bottom of the well bore, by controlling theweight of tool 10, as indicated, at the top of the well by drill weightindicator 19.

When valve means 35 is closed, a pressure equalizing valve arrangement,particularly illustrated in Fig. 7, is arranged to be opened by theretraction of valve stem 61 to its original position so that the inletport means may again be at the same pressure as the drilling fluid. Thisfeature is particularly desirable to prevent the difference inpressures, established during the formation test, from holding the toolon bottom. As shown, a lever arm 94, pivoted on pin 95, is normally heldin a horizontal position by spring 93, but during the opening of mainvalve means 35, arm 94 is permitted to trip past lever 97 which islinked through bracket 98, and connecting rod 92 to sliding valve 91.Valve member 91 is held in the illustrated position by a stop on bracket98 and the difference in fluid pressure between chamber 50 and the borehole before and during the formation test. However, when main valve stem61 is retracted to its original position, equalizing valve 91 is forcedoutwardly by the linkage including connecting rod 92 to the positionillustrated in phantom, so that conduit is placed in free communicationwith chamber 50 and the pressure equalized be tween the inside andoutside of packer means 28.

In this way, the fluid sample entrapped in the interior of the drillpipe may be readily withdrawn as the drill pipe is raised anddisassembled at the top of the well. Accordingly, a full test of thefluid content of formation 11 may be made at any stage during thedrilling operation, without the necessity for drilling a rat-hole, orthe necessity of running special packer arrangements thereinto to obtaina satisfactory seal-off against the static head of drilling fluid.

Referring now to the packer arrangements illustrated in Figs. 4, 5, and6, there are shown various modifications of the bottom-hole engagingmeans, or packer means, 28 and the inlet port means formed therein,which may be used in various types of earth formations whose fluidcontent is to be sampled. In the arrangement of Fig. 4, it will beobserved that there is provided an additional ring or annular cuttermeans 75 which is substantially the same diameter as the lower end oftool 10. This arrangement permits drilling into the bottom-holeformation for a distance sufficient to permit penetration of the zoneinvaded by the drilling fluid and lying directly behind the mudcake 47.In some very porous formations, this arrangement is highly desirable,since the invading fluids from the drill hole may prevent the taking ofan adequate sample, due to the hydrostatic head in the well bore holdingback the formation fluid. Accordingly, the arrangement of Fig. 4 permitsa better penetration into earth formation 11.

In the arrangement of Fig. 5, there is provided analternativearrangement for preventing rotation of lower portion 26, when it isdesired to counter-rotate upper section 30 to open valve 35 and firecharge 37. As illustrated, a plurality of spikes 80 may be forceddownwardly into the formation.

As illustrated in Fig. 6, the lower end of testing tool may be seated insome types of formations without the necessity of drilling an annulararea, such as those formed with the equipment illustrated in Figs. 2 and4. Under these circumstances, the packer means 28 is provided with acircular opening 28a which in part forms an inlet port means throughwhich the shaped-charge 37 may be fired directly against earth formation11. This arrangement of inlet port means may, of course, be varied inaccordance with the formation under test, and as particularlyillustrated in the arrangement of 'Fig. 5, may be formed by charge 37perforating the packer means 28, which may be solid throughout the endface 25 of bore hole tool 10.

From the foregoing description, it will be seen that an apparatus hasbeen provided for testing formations lying at the bottom of a bore holewherein a packer means for sealing the lower end of the body member ofthe testing tool is held in firm engagement against the bottom bycontrol of the vertical thrust on the body by regulation of the verticalload applied to the derrick draw works. The apparatus is furthercharacterized by there being provided means for relieving thehydrostatic pressure on the formation, including perforating meanspositioned immediately behind the packer means, capable of opening aninlet conduit to the interior of the tester body. The testing apparatusfurther includes means for actuating, or energizing, the perforatingmeans to pierce the bottom of the bore hole, as well as means foropening said body to admit fluid and for closing the lower end of saidbody member to entrap formation fluid within the body of the testingtool and the drill pipe upon which the body memher is supported.Pressure equalizing valve means, operable when the main valve recloses,are provided to permit ready removal of the tool from the bore hole.

Various modifications and changes in the foregoing apparatus will occurto those skilled in the art from the foregoing detailed description.Among such modifications which may be made without departing from thescope of the invention, is the means for exploding the shaped-chargewithin the body of the tester tool. The foregoing description hasparticularly illustrated and described the use of shaped-charges, but itwill be apparent that other types of piercing, or perforating apparatus,such as gun perforating means, may be employed, and that the detonationthereof may be accomplished by the application of concussion orelectrical energy.

Other modifications and changes may be made without departing from thescope of the invention, and all such modifications falling within theterms of the appended claims are intended to be included therein.

I claim:

1. Bottom hole formation testing apparatus comprising a body member, adrill pipe, means supporting said member from the drill pipe for axialand rotational movement relative thereto in a full-sized bore hole, saidbody member including an end face, having a diameter substantially lessthan the diameter of the bore hole in which it is to be employed, adeformable packer means covering a substantial portion of said end facefor sealing said body member into engagement with an earth formation atthe bottom of said bore hole, said deformable packer means having anormal diameter substantially the same as the diameter of said bodymember and having a thickness substantially less than the diameterthereof to prevent engagement with the side walls of said full-sizedbore hole when said packer means is deformed on bottom, means forseating said body member on the bottom of said bore hole includingweight control means for applying a predeterminable vertical thrust onsaid body member to deform said packer means, a fluid-receiving chamberextending axially through said body member and communicating With theinterior of the drill pipe, formation perforating means secured to andforming a portion of the end face of said body memher, said perforatingmeans closing 01f the lower end of said fluid-receiving chamber andforming a plug therein, said packer means being in direct contact withat least a portion of said perforating means, means for actuating saidperforating means to successively shatter the plug to form an inlet portmeans in said end face of said body member and to pierce the bottom ofsaid bore hole to permit flow of formation fluids into the interior ofboth said fluid-receiving chamber of said body member and said drillpipe, normally open valve means in the line of communication betweensaid fluid-receiving chamber and said drill pipe and means operable byrelative movement between said body and said drill pipe for closing saidvalve means to entrap formation fluid.

2. Bottom hole formation testing apparatus comprising a body memberadapted to be supported by a drill pipe in a full-sized bore hole, saidbody member having a diameter substantially less than the diameter ofthe bore hole in which it is to be employed, deformable packer means forsealing the lower end of said body member into engagement with thebottom of said bore hole, said deformable packer means having a normaldiameter substantially the same as said body member and having athickness substantially less than the diameter thereof to preventengagement with the side wall of said full-sized bore hole when saidpacker means is deformed on bottom, weight control means for applying apredeterminable vertical thrust on said drill pipe and said body memberto deform said spacker means and senlingly engage said packer with thebottom of the bore hole, a fluid-receiving chamber extending axiallythrough said body member and communicating with the interior of saiddrill pipe, explosive formation perforating means secured in the lowerend of said fluid receiving chamber, said packer means being in directcontact with at least a part of said perforating means, verticallymovable means within said body member for exploding said perforatingmeans to successively open said fluid-receiving chamber to the bottom ofthe bore hole and to pierce the bottom of said bore hole to permitformation fluids to flow through said chamber to the interior of saiddrill pipe, normally open valve means in the line of communicationbetween said fluid-receiving chamber and said drill pipe and meansoperable by relative movement between said body and said drill pipe forclosing said valve means to entrap formation fluid within. said bodymember and said drill pipe, and means associated with said valve means,operable in response to relative movement between the drill pipe andsaid body for actuating said vertically movable means.

3. Bottom hole formation testing apparatus comprising a body memberadapted to be supported by a drill pipe in a full-sized bore hole, saidbody member having a diameter substantially less than the diameter ofthe bore hole in which it is to be employed, deformable packer means forsealing the lower end of said body member into engagement with thebottom of said bore hole, said deformable packer means having a normaldiameter substantially the same as said body member and having athickness substantially less than the diameter thereof to preventengagement with the side wall of said full-sized bore hole when saidpacker means is deformed on bottom, weight control means for applying apredeterminable vertical thrust on said drill pipe and said body memberto deform said packer means and sealingly engage said packer with thebottom of the bore hole, a fluid-receiving chamber extending axiallythrough said body member and communicating with the interior of saiddrill pipe, explosive formation perforating means secured in the lowerend of said fluid-receiving chamber and forming a plug therein, saidpacker means being in direct contact with at least a part of saidperforating means, means for energizing said perforating means tosuccessively open said fluid-receiving chamber to the bottom of the borehole and to pierce the bottom of said bore hole to permit formationfluids to flow through said fluidreceiving chamber to the interior ofsaid drill pipe, normally-open valve means between said fluid-receivingchamber and said drill pipe, means operable by relative movement betweensaid body member and said drill pipe for closing said normally-openvalve means to entrap formation fluid within said drill pipe, anauxiliary conduit between said fluid-receiving chamber and the borehole, and normally-closed valve means in said conduit, saidnormally-closed valve means being operable in response to closing ofsaid normally-open valve means for opening said fluid-receiving chamberto fluid in the bore hole to equalize the pressure difference acrosssaid packer means.

4. Apparatus for testing the fluid content of an earth formation lyingat the bottom of a full-sized bore hole comprising a body member adaptedto be supported by a drill pipe in full-sized bore hole, said bodymember including the lower end face having a diameter to permit passageof said body to the bottom of said well bore without substantialinterference with the side walls of said bore hole, a deformable packermeans covering a substantial portion of said lower end face of said bodymember and adapted to be deformed to seal the end of said body memberinto engagement with the bottom of said bore hole without engaging theside walls of the well bore, said deformable packer means having anormal diameter substantially the same as the diameter of said bodymember and having a thickness substantially less than the diameter ofsaid body member to prevent engagement with the side wall of said borehole when said deformable packer means is seated on bottom, weightcontrolling means for applying a predeterminable vertical thrust to saiddrill pipe against the bottom of said bore hole to deform said packermeans against the bottom and into sealing engagement therewith, afluid-receiving chamber extending axially through said body member andcommunicating with said drill pipe, frangible plug means in the lowerend face of said body member to close said chamber, perforating meansfor successively shattering said plug to form entrance port means intosaid chamber and piercing the bottom of said bore hole to permit aportion of said formation at the bottom of said bore hole to be relievedof the hydrostatic head exerted on said formation by drilling fluid insaid bore hole, a stem section, having a conduit formed therein,vertically movable in said body member, said conduit in one positionthereof being connected to said chamber to com municate with said drillpipe, and in another position thereof being adapted to preventcommunication between said chamber and said drill pipe, said sternsection being connected to said drill pipe, so that relative movement ofthe drill pipe with respect to the body will move said section to theaforesaid position of communication, vertically movable means foractuating said perforating means operable in response to a furthermovement of said stem section beyond its position of communication, anormally closed conduit formed in a side wall of said body memberbetween said chamber and the exterior of said body, and normally closedvalve means in said conduit for admitting fluid in said bore hole tosaid chamber operable in response to reverse movement of said stemsection to the aforesaid other position to equalize the hydrostaticpressure inside and outside of said body member.

5. Bottom-hole formation testing apparatus comprising a body memberadapted to be supported by a drill pipe in a full-sized bore hole, saidbody member having a diameter substantially less than the diameter ofthe bore hole in which it is to be employed, deformable packer means forsealing the lower end of said body member into engagement with thebottom of said bore hole, said deformable packer means having a normaldiameter substantially the same as said body member and having a lengthsubstantially less than the diameter thereof to prevent engagement withthe side wall of said full-sized bore hole when said packer means isdeformed on bottom, weight control means for applying a predeterminablevertical thrust on said drill pipe and said body member to deform saidpacker means and sealingly engage said packer with the bottom of thebore hole, a fluid-receiving chamber extending axially through said bodymember, means providing communication between said chamber and theinterior of the drill pipe, explosive formation perforating meanssecured to the lower end of said body member and forming a plug in thelower end of said fluid-receiving chamber, said packer means being indirect contact with at least a part of said perforating means, saidcommunicating means including a vertically movable valve means in saidbody member intermediate said drill pipe and said perforating means,said valve means being operable by said drill pipe responsive torelative rotation between said body member and said drill pipe in onedirection to open when said body member is sealed on bottom, firing pinmeans operable in response to said movement of said valve means beyondits open position for exploding said perforating means to suecessivelyshatter said plug to form port means into the interior of saidfluid-receiving chamber and to pierce the bottom of the bore hole topermit flow of formation fluids through the pierced bottom of said borehole into said chamber and said drill pipe, a pressure equalizingconduit between said fluid-receiving chamber and said bore hole, andnormally-closed equalizing valve means in said conduit operable inresponse to reverse rotation between said drill pipe and said bodymember, and means operable in response to relative movement of saiddrill pipe and body member in an opposite direction to close said firstvalve means, for actuating said equalizing valve means to open thelatter.

References Cited in the file of this patent UNITED STATES PATENTS1,347,534 Cox July 27, 1920 2,274,339 Loomis Feb. 24, 1942 2,367,733Munn Jan. 23, 1945 2,441,894 Mennecier May 18, 1948 2,544,573 VincentMar. 6, 1951 2,674,313 Chambers Apr. 6, 1954

